MrTantrum

Have a new-to-me 2008 535i with brand new offset tires (still have all the little rubber pieces sticking out on the sidewalls and perfect treads). This is my first car of this quality/class, and I don't know much about tires in general. How do I know if these the tires on my car are RFS or not - is it written on the tire somewhere?

From what I can read on the sidewalls, the tires are as follows (not sure why they put different brands on):

Rear: Michelin Pilot Sport A/S Plus 275/35 ZR18 95Y M+S
Front: Dunlop SP Sport 01 DSST 245/40 R18 93Y

Also, while I understand that the rear tires are 30mm wider, did they go with the lower tire height ratio on the rear to get them as close as they could be to being the same circumference as the front tires (e.g 275*.35=96.25mm vs. 245*.4=98mm)? Is this just for even wear, some other reason, or does it matter at all?

vkhong

DSST stands for Dunlop Self-Supporting Technology (run-flat). Michelin Pilot Sport A/S Plus is not run-flat.

245/40-18 and 275/35-18 is the BMW fitment for staggered wheels. The 93Y and 95Y ratings appear to be in line with BMW's.

pukka

M+S stands for Mud & Snow, which is a required rating in some areas where you experience winter driving conditions. It's NOT the same as actual snow tires. Either the original owner put those tires on for better traction or it was just considered a less expensive substitute over run-flat tires.

The Dunlop's are OEM tires for your car.

luigi524td

Your set-up seems to be a mix of conventional and run flat (DSST) AND all-season/Mud & Snow AND maybe "summer" tires ... That, while not totally dangerous, may result in unsettling handling - especially at the limits. If you bought it as a BMW CPO, IMHO, all four tires should have been a match.

MrTantrum

Thanks for the info, thus far. I live in DFW area in TX, so snow/ice is a one to two time per year occurance at the worst. Maybe it came down to an availability issue at the time when the replaced the tires, because the Dunlops are brand-new also (can tell by the tread and little sidewall rubber thingies that stick out - non-technical name, of course.) Also, I do know that the previous owners were older, so maybe they thought M+S on the rear would be a little safer for them.

I did not purchase the car from a BMW dealer as CPO. However, the original dealer is local and I contacted them for the service history on the vehicle. They were very open with me (as a FYI, I previously owned another vehicle that I purchased from them). The car had all recalls applied and a maticulous service history with a pristine mechanical history, as well. Also, given who the original owers were (you can find out a lot these days with just a name and Google), I doubt that saving a few bucks was even a thought when it came to replacing the tires. It just confuses me why they didn't match them all. Even though all four appear to be brand-new, maybe they were purchased at slightly different times or at different places - who knows.

flyingpuck

My suggestion....if you have a blowout, have it in a front tire!

MrTantrum

I don't know . . . it might look kind of cool driving around town with that donut spare on the backend of my bimmer!

rrnag30

very strange - thought it was common knowledge to match up all 4 tires to have the same tread for traction and wear purposes.
+1 on Luigi's statement having the two brands will not be dangerous..I am willing to bet depending on how you drive you will not even "feel" the difference. If you do not track your car you will be fine..if you can stomach knowing and seeing the fact you have different tires. Would drive me crazy with my OCD

MrTantrum

Typically very OCD myself, but I really have to look to notice the difference. Also, being that this is my first "performance sedan", I really don't know what it is suppose to feel like. What I can tell you is that in straight line speed, it feels awesome. However, I haven't had to do much cornering. Also, this car will typically never get above the speed limit as it is primarily my wife's vechicle.

Rez

I also bought my 535i just in October. Fortunately, the car had a spare, and I replaced all 4 tires with the non-run-flat Michelin Pilot A/S Plus you have on the back.The ride has become a lot quieter than having the run flats it came with. Handling is still very very responsive. I am also in the DFW area and based on our winter/ snow record, decided to go with these All Season tires.